The present invention generally relates to pointing devices and, more particularly, to a pointing device which is used to move a pointer or cursor on a display of a computer or the like to an arbitrary position on a display screen.
Generally, the input and output of data, in data processing by a computer, are carried out interactively. For example, the input is made from a keyboard of the computer and the pointing device is manipulated while displaying data such as characters and graphics on the display screen, such as a cathode ray tube (CRT), so as to move the pointer or cursor to an arbitrary position on the display screen. A digitizer, a mouse, a lightpen and a track ball are examples of the pointing device. The interactive data input and output are often used in fields including computer aided design (CAD) which processes data such as graphics, computer aided manufacturing (CAM), and simulation.
Recently, in addition to the keyboard, it has become popular to use the pointing device as the data input device in fields such as data processing and office automation (OA). The reason for the popular use of the pointing device is due to the extremely convenient operation of operating systems (OS) and application software which carry out processes in response to interactive operations for which the use of the pointing device is essential. For example, window operations and icon operations are examples of the interactive operations.
On the other hand, the computer is not necessarily limited to the desk-top type having independent computer body, keyboard and display. Recently, portable computers such as the lap-top type, notebook type and palm-top type have become popular, and such portable computers have an integrated computer body, keyboard and display. The portable computer such as the lap-top type is convenient to carry because it is light and compact.
However, due to the emergence of the portable computers such as the lap-top type, the environment in which the pointing device is used has become more varied. In other words, in the desk-top type computer, the pointing device simply needed to be placed on the desk top similarly to the computer, and manipulated on the desk top. However, for the portable computer, it is necessary to manipulate the pointing device in a state where the computer is placed on the user's lap top or hand.
For this reason, it is desirable that the pointing device used with the portable computer does not require a set-up area, like the mouse and digitizer used with the desk-top type computer, and that the pointing device used with the portable computer, instead, can be assembled within the portable computer. In addition, there is also a demand to reduce the set-up area, on the desk top, of the pointing device that is used with the desk-top type computer, and it is desirable to assemble the pointing device within the computer in order to meet such a demand.
FIG. 1 is a perspective view showing an example of a conventional pointing device.
In FIG. 1, a rectangular column-shaped stick 502 is made of a resin, and a base portion of this stick 502 is fixed on a base 501 of a keyboard or the like. The stick 502 has a square cross section, and a strain gage 504 is provided on each side surface of the stick 502. Only 2 strain gages 502 are shown in FIG. 1.
When the operator places his finger tip on the tip end of the stick 502 and displaces the tip end in an arbitrary direction, a strain dependent on the force applied on the tip end of the stick 502 is generated at each strain gage 504. Since the resistance of the strain gage 504 changes depending on the degree of strain, it is possible to determine the moving direction and moving distance of the cursor or pointer on the display screen based on the changes in the resistances of each of the strain gages 504 by detecting the change in the resistance of each strain gage 504.
However, in the conventional pointing device, each strain gage 504 must be adhered on the corresponding side surface of the stick 502. For this reason, there were problems in that it takes time to adhere the strain gages 504 on the stick 502, the adhering process makes it difficult to mass-produce the pointing device, and it is difficult to produce the pointing device at a low cost. In addition, since the strain gage 504 is adhered on the side surface of the stick 502 by use of an adhesive agent or the like, a mounting error is inevitably introduced among the strain gages 504, and there was a problem in that the strain detecting accuracy is poor. These problems of the conventional pointing device became more conspicuous as the size of the pointing device became smaller.
On the other hand, it is conceivable to directly form each strain gage 504 on the side surface of the stick 502 using techniques such as evaporation and sputtering. In this case, it is necessary to uniformly control the film thickness of the pattern which forms the strain gage 504 at each side surface of the stick 502 so that the characteristics of each of the strain gages 504 will be approximately the same. However, when forming the strain gage 504 by evaporation or sputtering, it is extremely difficult to uniformly control the film thickness at each of the side surfaces of the stick 502. For this reason, the characteristics of the strain gages 504 that are formed by the evaporation or sputtering will become inconsistent, and the strain detecting accuracy will become poor.
In addition, when directly forming each strain gage 504 on the corresponding side surface of the stick 502, it becomes necessary to use a special jig to hold the stick 502 while the evaporation or sputtering is carried out. In this case, it takes time to carry out the operation of fixing the stick 502 on the special jig, and the pointing device becomes unsuited for mass production and it is difficult to produce the pointing device at a low cost.